170 Proceedings of Royal Society of Edinburgh, [april 4, 
out gradually passing backwards, and finally becomes dilated into an 
oval sac. The spermathecse sometimes lie straight, and are some- 
times coiled into a circle. The walls of the spermathecse are 
very thin, owing to the slight development of muscles and the 
character of the lining epithelium, consisting as it does of flattened 
cells ; these structural features, together with the superficial covering 
of rounded, vesicular, peritoneal cells, and the general shape of the 
organs, gives the spermathecse a very strong resemblance to the 
diverticula of the nephridia figured by myself in Acanthodrilus 
novce-zelandice .* * * § In view of a possible homology between the 
spermathecse and such diverticula, it is worth while to record the 
points of similarity between the two series of organs. Further- 
more, I may remark that in a large number of individuals, all fully 
mature, there was no increased development visible in the sperma- 
thecse, which undoubtedly have a certain appearance of immaturity. 
The general shape of the spermathecse is very like that of the 
spermathecse of Diachceta , f but they appear to be considerably 
smaller in the present species, and also differ in that their aper- 
tures on to the exterior are at the anterior, instead of at the 
posterior, boundary of their respective segments. 
In Urochceta corethrurus $ there are also three pairs of sperma- 
thecc© not unlike those at present under discussion in shape, and 
opening like them at the anterior margin of their segment ; they 
are situated, however, rather further back (in segments 8, 9, 10) ; 
further, in both Urochceta and Diacliceta the spermathecal segments 
contain nephridia. 
Perichceta neiucombei,§ n. sp. 
This species is represented by eight individuals, of which four are 
sexually mature, with a fully developed clitellum. 
The colour of the species is a dark purple upon the dorsal surface, 
gradually passing into a yellowish-brown upon the ventral surface ; 
the intersegmental furrows dorsally, as well as ventrally, are of the 
* Proc. Zool. Soc., 1885, pi. lii. fig, 5. 
+ Benham, loc. cit., pi. ix. fig. 29. 
+ Perrier, Arch. d. Zool. Exp., t. iii. (1874), p. 518, pi. xiii. fig. 12 pc; 
pi. xvii. fig. 49. 
§ Named after Mr S. Prout Newcombe. 
